Drive coupling mechanism



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L. H. sco'r'r v DRIVE COUPLING MECHANISM Filed June 11, 1942 e Sheets-Sheet 4 Z l w R I. w 0 0 V. 7 .m & wm E v a ,Ww W 8 4 .1 1;: 1 1 I :l 0 EEPE n a0 M a 4 I] 41 v. am J 3 B I a m 2 3 0 0 7 W 7 7 5 7 Z I z W 2 w Jan. 22, 1946. L. H. scoTT DRIVE COUPLING MECHANISM 6 Sheets-Sheet 5 Filed June 11, 1942 Z/ayd [Z 5 HTTORNEYS Patented Jan. 22, 1946 DRIVE COUPLING MECHANISM Lloyd B. Scott, Garden City, N. Y., assimor to Eisemann poration of Delaware Corporation, Brooklyn, N. Y., a cor- Application June 11, 1942, Serial No. 446,579

16 Claims.

The present invention relates to angular phase shifting drive coupling mechanism particularly adapted tor automatically effectingin a predetermined manner certain different angular shiftings of driven and driving elements with respect to each other; and the present application is a continuation-in-part of my copending application Serial No. 417,751, filed November 4, 1941.

A general object of the invention is the provision of such a device which is of simple and rugged construction readily adapted to economical commercial production, is eflicient and positive in operation and capable in a ready manner of effecting between driving and driven elements a great variety of angular phase changes comprising angular shiftings in opposite directions,

- system 'are dynamically balanced, and weight and is adapted for many uses including easy interpositioning between the driven rotor of a magneto or distributor in the ignition system of an internal combustion engine and an engineoperated driving shaft for selectively timing the spark. 4

A more specific object of the invention is the provision or such a device characterized by a driving element and a driven element associated with means to effect different phase relationsbetween those elements and drive one from the other in such relative positions, such means comprising a centrifugal lever member floatingly mounted at a plurality of different places and cooperating with means for automatically causing the lever member to be fulcrumed selectively and alternately at such places at different speeds angularly to advance and retard one element relative to the other.

Another object is to provide a mechanism of the character indicated which is operated centrifugally and is provided with a centrifugal lever member and a plurality of fulcrum automatically coming into operation at 'de ed instants and so arranged relative to a work locale as to cause said lever member alternately to act as a lever 01' the first class and a lever of one of ;the other two classes, i. e. second and third classes, to change the angular relationship between driving and driven elements for a given .speed range.

A further object of the invention is the provision of such a mechanism which may be utilized efiectively to advance and retard the spark timing for an internal combustion engine in a predetermined manner or in accordance with a predetermined characteristic curve; 7

An additional object of the invention is to provide a unitary mechanism of the character indicated which will automatically advance and as in elevational. section;

retard the spark timing over a plurality of speedv ranges such as may be desired in the field of aviation.

Still another object of the invention is'to provide a mechanism of the character indicated as asmall, compact, light weight unit that may be easily attached to standard equipment in an ignition system, such as to a magneto for airplane service, whereby the desired characteristic performance is made attainable.

A still further object is the provision of such a device wherein fulcrumed weights of a weight biasingmeans are so related to the other parts that should such biasing means fail in an ignition service the device will operate in a manner to avoid serious engine operating diillculties.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated inthe claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detaileddescription taken in connection with the accompanying drawings, in which? Fig. 1 is an end elevational view of one modification of the mechanism of the present invention;

Fig. 2 is an elevational view from the opposite end of the unit shown in Fig. 1 showing in section one oi the driven and driving shafts connected thereto;

Fig. 3 is a sectional view taken on line 3-3 of Fig. 2;

Figs. 4, 5 and 6 are detailed views showing plans of elements of the assembly shown in Figs. 1, 2 and 3;

Fig. 7 is a diagrammatic view showing a three range angular advance-speed characteristic curve indicating automatically'achieved changes by mechanism of the present invention in connection with its use as associated with the ignition system of an airplane;

Fig. 8 is an end elevational view of another modification of the mechanism of the present invention;

Fig. 9 is a side elevational view with parts broken away of the structure shown in Fig. 8, and as located in a suitable casing structure shown of Fig. 8, with a sectional view of the casing structure shown in Fig. 9; p

Fig. 11 is a sectional view taken on line ll-ll of Fig. 10;

Fig. -l2 is a sectional view taken on line i2--l2 of Fig. 9,with the omission of the casing strucure;

Fig. 13 is a side elevational view of a further modification of the mechanism of the present invention;

Fig. 14 is a sectional viewtaken on line il-ll of Fig. 13, with parts broken away;

Fig. 15 is a side elevatlonal view with parts broken away of a further modification of the present invention;

Fig. 16 is an end elevatiohal view of the structure shown in Fig. 15;

Fig. 17 is a sectional view taken on line ll-ll v of Fi 16;

Fig. 18 is a sectional view taken on line l8-II of Fig. 1'7;

Fig; 19 is a sectional view taken along the axis of a further modification of the coupling device of the present invention, the line of sectioning being indicated in Fig. 20;

Fig. 20 is a sectional view taken alon 20-20 of Fig. 19; and

Figs. 21 to 24, inclusive, are diagrammatic showings of the four possible leverages of the present invention whereby advance and retard or angular shiftings in opposite directions of coupling elements relative to each other may be attained.

In many fields wherein a driven element is coupled to a driving element for rotation of one by the other it may be desired during rotary operation angularly to shift one relative to the other in opposite directions in accordance with a predetermined plan of operation; or to accomplish differing angular phase shifting, comprising advancing and retarding; in different speed ranges.

line

The present invention is admirably suited to such purposes and to accomplish such ends automat-' ically, the speed of the rotating members in a particular mechanical assembly inclusive of the device of the present invention being the chief governing factor in the selective operation of the latter. By way of example, the present invention may be of advantageous use in the field of aviation ignition.

It is generally desirable when airplane engines are starting or turning over at very slow rates of speed to cause the spark to occur at a small degree of advance beforetop dead center of a piston head is reached. Such advance is preferably constant from zero engine speed up to a certain engine speed substantially above maximum idling speed. In order to obtain maximum engine horse-power at full throttle condition such as desired on take-off the advance must be increased to a certain setting. Under cruising conditions where maximum engine horse-power is not required a higher fuel economy may be attained by afurther increase in the spark timing advance over that required for maximum horse-power.

A speed angular-displacement characteristic which may be attained with the use of a particular modification of the invention and may be desired for certain airplane service is shown in Fig. '7, by way of example, as a three-range curve. Such curve has an initial portion showing speed I ranging up to say about 800 R. P. M. in which the angular advance for the spark is to be constant and have a value of about This covers the cranking speed range of about from to 50 Fig. 10 is a sectional view taken on line Iii-HI R. P. M. and idling speed range 01' about from 300 to 800 R. P. M. From this value the advance is to be shifted to a maximum of about 35 at say 1,000 R. P. M. suitable for warm-up. This increased advance value obtains until the speed is about 2,000 R. P. M. when a retardation of the spark is to begin to take place. This latter continues until the advance is about 20 at a speed of about 2.200 R. P. M. and thereabove suitable for take-oil during which maximum horse-power is demanded requiring the use of a relatively rich fuel mixture. The characteristic curve just described depicts the manner of spark control which may be desired in a magneto for a modern airplane engine. Many of such engines have cruising speeds of 1,000 and 2,000 R. P. M., say about 1,700 to 2,000 R. P. M., with the use or a relatively lean fuel mixture which latter requires a greater spark advance than when richer fuel mixtures are used. This explains the reason for the advance of the'spark to about 35 at the intermediate speed range, that is during cruising; and is suitable though not essential for warm-up and does not introduce operating difiiculties even though the advance has to go through that increase to 35 other, means at a plurality of different places flcatingly mounting the lever member relative to one of the coupling elements, and means automatically causing the mounting means during rotary movement of the coupling elements selectively and alternately to act as fulcrums with the lever member acting at diflerent speeds as a lever of the first class and a lever of another class to advance and retard the angular relationship between the coupling elements. In accordance with the present invention, the fulcra,'the center of mass of the lever member-and the effective point of driving connection between the lever member and one of the coupling members he on different, angularly-related radii extending from a point on the axis of rotation of one of the coupling elements. The radius on which one of said fulcra lies is disposed within an angle between the radii on which the center of mass and the point of driving connection lie. The other fulcra radius is disposed outside the above mentioned angle between the center of mass radius and the point of driving connection radius.

The device of the present invention may have but one weight system and hence may be relatively light and of simple construction. It-may be built as a detachable unit readily mountable in the drive of a magneto or distributor of the ignition system of an airplane engine. Thus the innected thereto. comprise a linkage hereinafter described which shaped complementary to the portion II of the shaft I8 may comprise the driven element of the coupling mechanism. Sleeve I2 may have one or more integrally attached arms I3, I3 through which the driving force is transmitted by any suitable means operatively associated or con- One such suitable means may operates to effect a desired phase shift or angular adjustment of the shaft I relative to another member such as the driving element here shown as comprising a member or plate I4 provided with a driving sleeve I5 rotatably disposed on a reduced portion I8 of shaft I0 preferably by means of an interposed bearing sleeve I1 and held thereon by a thrust washer I8 and a nut I8 threaded on a further reducedportion 28 of shaft I0. One or more members responsive to speed and arranged to control the angular phase shift in a manner corresponding with a desired speed angular-displacement characteristic in accordance with the invention are floatingly associated with member or plate I4.

Thespeed responsive member or members which, by way of example, are shown floatingly associated with respect to one of the coupling elements comprise one or more centrifugal weight or lever members 2|, 2|, preferably two in number, symmetrically arranged with respect to each other so that the mechanism may readily be balanced dynamically. Each of the weight members 2|, 2| is shown floatingly mounted at a plurality of different places with respect to the driving coupling member II. This may be accomplished by means of pins 22 and 23 which respectively work in ways such as slots 24 and 25 in the member I4. The sides of the slot 25 are defined by circular arcs circumscribed ab'out thecenter of pin 22 in its innermost position and the sides of slot 24 are defined by circular arcs circumscribed about the center of pin 23 when in its outermost position in slot 25. The weight members 2|, 2| are seen to be subject to centrifugal forces when the coupling mechanism revolves, the pins 22, 22 and 23, 23 serving as floating fulcrums at two different places.

Each weight member 2| is bifurcated at the end remote from the first fulcrum pin 22, as shown at 26, in order to embrace and be pivotally attached at a work locale or point 21 to one end of thereto, such asa magneto rotor.,provides the biasing through shaft II, sleeve I2, arms l3, I3 and links 23, 28 for the pins 23, 23. The biasing due either to force exerted by a driven device or to such springs are so related in strengths to the mass of the centrifugal lever members as to hold the fulcrum pins stationary against centrifugal force and then permit selective movement there of and have them alternately serve as fulcrums through predetermined speed ranges. If desired. however, springsmay be used also for pins 23, 23 to increase the biasing thereof or the biasing due to reactive torque of the driven device or magneto rotor may be reduced by the use of resilient means between the driving and driven elements as is more fully pointed out hereinafter.

In a structure asdepicted in Figs. 1 to 6, inelusive, the biasing force due to the springs 30, 38 attached to pins 22, 22 may be made the shorter and may have a strength-such as to yield only to the value of the centrifugal force acting'on the weight arm at about 2,000 R. P. M. and to be yielded fully through its operative range at about 2,200 R. P. M. and thereabove. The biasing force effective at the fulcrum pins 23, 23 at least in part due to reactive torque of the magneto rotor may be relatively weaker such as to be overcome by the centrifugal force of the weight arm obtaina link 28 which has its other end pivotally attached to the arm I3. Arm I3 is preferably receive the end of link 28 and to equalize the pull thereof. In this modification itwill be noted that the work locale or point 21 is to one side of both fulcruming places.

In order to impart selectivity in operation of the floating fulcrums each centrifugal lever member 2| is biased by a suitable biasing force at such places. For example, this may be accomplished by suitable springs between certain fulcrum pins and the member The structure shown in Figs. 1 to 6, inclusive; will operate effectively when pins 22, 22 are alone biased by springs 30, 30 each of which is shown attached to an outside end of one of the pins 22 and anchored to a wing 3| on sleeve I5. In such a case reactive torque of the driven element ,or device attached ing at about 800 R. P. M. and the centrifugal weight members 2|, 2| attains fully yielded positionsat pins 23, 23 through their operative ranges at say about 1,000 R. P. M. and thereabove. Thus the centrifugal weight levers 2|, 2| are so biased as to act as levers to do work or pull through links 28, 28, acting first as levers of the third class and then as levers of the first class whereby angular phase adjustments are made satisfying a three-range characteristic curve as depicted in Fig. 7. When the engine is revolving slowly or at a speed less than 800 R. P.-M. the biasing forces cause the fulcrum pins 22, 22 and 23, 23 to be held to innermost initial positions as shown in Fig. 2. Under such conditions the angular ad-. vance of the spark timing due to angular advancement of the magneto rotor and breaker and distributor elements carried thereby or otherwise driven therefrom is but 5, i. e. the spark from the magneto is occurring in its most retarded position. As the speed increases above about 800 R. P. M. the centrifugal force operating. on the weight arm overcomes the biasing force which mayat least be partially due to reactive torque of the magneto rotor with the slots 25, 25 permitting outward movement of the pins 23, 23 to their outermost positions. During such movement pins 22, 22 in their innermost positions serve as fulcrums and the weights 2|, 2] move as levers of the third class pulling upon links 28, 28 which rotate arms I3, l3 in a counter-clockwise direction as viewed in Fig. 2 imparting an angular phase shifting to shaft I 0 through sleeve I2 until at a speed of about 1,000 R. P. M. an angular advance of about 35 is had. This angular advance obtains for the second speed range up to about 2,000 R.'P. M. with the links.28, 28 pulling on arms I3, I3 to rotate the member I2 and magneto rotor therewith as the centrifugal lever members act as levers of the third class. At about 2,000 R. P. M. the centrifugal force has increased to a value such that it begins to overcome the biasing force due to springs 30, 30 which latter then begin to yield. Fulcrum pins 23, 23 are now in the outermost parts of slots 25, 25

' and here act as fulcrums while weights 2|, 2|

4 a,sos,s4 4

creased centrifugal force withslot fl, 24 permitting outward movement of pins 22, 22.

The ,device or magneto rotor .being driven by the coupling imposes a drag on thelinks 2|, 28 which is opposed by the biasing force of springs 20, 30 at pins 22. when the force due to this rotor torque and the centrifugal force acting at the center of gravity (c. g.) of each of the centrifugal lever members 2|, 2| together reach a value which overbalances the biasing force of springs 80, 30 the pins 22, 22 are caused to move outwardly in slots 24,24 to outermost parts of the latter where the outward parts of those slots then act as stops with the pins 22,' 22 in outermost positions. During this operation the coupling member l2, arms l3, l3 and links 28, 28 are permitted to lag in a reverse or clockwise direction as viewed in Fig. 2, to a retard position thus retarding the angular advance of the distributor from about 35 to 20. Thereafter the centrifugal lever members 2|, 2| act as levers of the first class with pins 22, 22 acting as fulcrums in their outermost positions to transmit power from the driving coupling member I to the driven coupling member l2 through pulling linkage 28, 28, and this advance of about 20 which is attained at a speed of about 2,200 R. P. M. obtains for speeds above the latter value.

The longitudinal dimensions of the slots 24, 24 and 25, 25 determine the outward travel of the centrifugal lever members thereat and thus also the degree of changes of the angular advance and retard. The outermost part of the arcuate way or slot 25 constitutes a fulcruming abutment for pin 23 shown in Figs. 1 and 2 in a fulcrum floating position (which in this modification is a low speed driving position) and the innermost part of the arcuate way or slot 24 constitutes a fulcruming abutment for pin- 22 with the outermost part of the latter slot constituting a stop for pin 22'. The terms inward," outward, innermost" and outermost. as used herein refer to radial directions as distinguished from axial directions.

ments, for example, the shaft which is operative- 1y associated with a lever member. such as by yoke l2, arm II and link 28, may constitute the driving element and the member ll to which the a lever member is floatingly mounted may constitutethe driven element.

Selective automatic advance and retard of a driven coupling element or member relative to a driving coupling element or member can also be had by a device wherein mechanism mechanically interposed between the driving member and the driven member of the coupling for rotationally driving the latter from the former comprises a centrifugal lever member floatingly mounted at l diiferentplaces relative to one of the coupling members selectively and alternately to operate as a lever of the first class and a lever of the second class. Depending upon which of the two coupling members is to constitute the driving element and the direction of rotation of the coupling device first advance and then retard of the angular relationship between the coupling members or vice versa can be had as predeterminately desired, of course with suitable provision forbiasing -25 at floating mounts as a particular case may declass. Structure capable of such performance will, by way of example, be hereinafter described.

Characteristic curves'having, for example, four ranges may be attained by providing the weight system with still another set of floating fulcrums suitably related to the other fulcrums and the mechanical driving connection or operative driving association of the weight system with one of the coupling elements and suitable biasing whereby the fourth range of adjustment is obtained at another speed. Any and all such characteristic operations will be featured by angular advance and retard with the centrifugal lever member operating at times as a lever of the first class and at other times as a lever of another or other classes,

It will be noted that should the springs break or i e. o d class and/or third class become unduly weakened due to strain in service the dynamically balanced weights will assume their outermost positions during flight giving a spark advance of about 20 which is a safe operating value thereby avoiding engine failure and consequent disaster. The importance of this safety feature will readily be understood.

As described the structure shown in Figs. 1

to 6, inclusive, permits operation of the lever members first as levers of the third class fulcruming around pins 22, 22 and then as levers of the first class fulcruming around pins 23, 23.

' This operation can be reversed so that the lever members first operate as levers of the first class and then as levers of the third class. The latter may be accomplished by using biasing springs fulcrum points. It is also believed to be obvious that such a device will operate in a desired manner with a reversal of the driving and driven ele- Obviously the pivot or fulcrum pins 22, 22 and 23, 23 may be fixedly carried by the coupling member I and be received in suitable arcuate slots in the centrifugal weight members 2|, 2|

with suitable provision of biasing of the pins in y the slots. For this purpose resilient means such as springs may bias certain or all of the pins in such slots to inward positions, Such springs may be spiral compression springs positioned in such slots between the pins and the outermost ends of the slots, or tension springs each having one end connected to a pivot pin and the other end connected to some portion of the weight member inwardof the arcuate slot therefor. Of course the so biasing of the pins either by a spring at one pin and reactive torque of a driven device at the other pin or by springs at both pins with the biasing force of one supplemented by the biasing force due to reactive torque of the driven device must be adapted selectively to be overcome by centriffulcrums is referred to herein as fbiasing means.

Such a modified structure as suggested immediately above is shown by way of example in Figs.

8 to 12, inclusive. As in the first modification, coupling member or sleeve 2 is secured on" a. portion ll of the shaft l0 such as by splining and carries a pair of arms I3, I3 which are linked by a pair of links 23; 23 to a pair of centrifugal lever members I2I, I2I. Each of said centrifugal lever members I2I, I2I is floatingly associated with a second coupling member II4 by a pair of fulcrum pins I22 and I23 flxed to an end plate 32 and internally bored and threaded to anchor stud bolts 33-33 extending through the coupling member H4. The fulcrum pins I22 and I23'thus suitably space the end plate 32 from the coupling member H4 and fix it thereto for operative location therebetween of the centrifugal lever members I2I, I2I each of which is provided with a pair of arcuate slots I24 and I25 respectively receiving the fulcrum pins I22 and I23.

each having a v-shaped groove on the inner side thereof, as shown in Fig. 10, to cooperate with the conical faces 52 'and 55 to clamp flanges 53 and 53 together in frictional engagement for rotation The reactive torque of the driven device inclusive of the magneto rotor is relied upon for biasing the centrifugal lever members I2I, I2I at the fulcrum pins I23, I23 and suitable spring devices are used for biasing at the fulcrum pins I22. I 22. The latter may each comprise a spiral spring 34 having the inner end thereof seated in a slot in the shank 35 of a conicall'y headed or machine bolt 33 which traverses an end 31 of the centrifugal weight member I2I bifurcated at 33 for reception of the spring and associated structure. The other end 39 of the spiral spring 34 is hook-shaped to be received beneath the transverse bar 43 extending between side arms 4|, H of a U-shaped clip member loosely mounted upon the bolt shank 35 with the transverse bar 43 riding against the fulcrum pin I22 to bias it in the outermost part of slot I24. Adjustment of the biasing force can be had by the provision of a screw-driver slot 42 in the head of the bolt 33 and a lock nut 43 on the threaded shank 35 thereof. When the structure is assembled suitable tension is applied to the spiral spring 34 by rotating the bolt 33 with a screw-driver and locking it in desired position by'the lock nut 43. With the parts in the relative positions shown in Fig. 12 pin I23 is in a fulcrum floating position in'the outermost part of slot I25 with the innermost part of the latter constituting a fulcruming abutment for that pin, and pin I22 is in a-f ulcruming position iii the outermost part of slot I24 with the innermost part of the latter constituting a stop for pin I22.

The effective force on the. centrifugal lever members I2I, I2I at the fulcrum pins I23, I23 due to reactivetorque of the driven device may be'reduced to a predetermined value by the use of a resilient member or spring between the driving and driven elements such as. a spiral spring 44 wrapped around the axis of rotation and placed under stress with one end 45 fastened to the end plate 32 such as by reception in a slot 43 and with the, inner end 41 of the spring suitably anchored to the coupling element II2 such Such structure one from the, other. The half shoes 53, 53 may be suitably secured together such as by pivoting but referably each is provided with a lug 5] over which is hooked aheel piece or link 53. Opposite ends of the half shoesv 53, 53 are provided with upstanding pierced ears 53, 53 through one of which is extended a stud bolt 33 threadably engaged into the other for adiustably clamping the half shoes 53, 53 on flanges 53, 53.

It will be understood that the operative driving association of the centrifugal lever members with one of the coupling members is not limited to theuse of a linkage as is best illustrated in Figs. '13 and 14. For example, a rack and pinion device may be used with a coupling member or sleeve 2I2 suitably splined on the portion II of. shaft I3 and provided with pinion teeth 3| engagedby rack teeth 32 on a rack 33 pivotally mounted such as at 21 to onev of two centrifugal lever members 22I, 22I.- A guide pin 54 similar in structure to fulcrum pins I22 and 'I23 and mounted similarly between end plate 32 and coupling member II4 assures proper engagement between the pinion teeth 3I and rack teeth 32 at all times. I

The linkage between the coupling sleeve mounted on the shaft I-3 and the centrifugal lever members as shown in Figs. 1 to 12, inclusive, and the rack and pinion device shown in Figs. 13 and 14, are two examples of the many suitable ways that such elements ma operatively be connected together or associated with each other for driving one from the other. For example, the operative driving association does not of necessity require direct connection since the desired operation may be attained by disconnected mechanism such as suitable cam'means hereinafter exemplified, and

the reduced portion I3 of the shaft I3 and held thereon by the thrust washer I3 and nut I3. Sleeve H5 is suitably splined' as shown for connection to' a driving member suitably operated, such as by'the engine, and the inner end 43 thereof rotatably supports the coupling member I I4. The driving sleeve H5 is provided with a flange 53 having a friction face 5I substantially lying ini'a flat plane and aconical face 52. A

the use of the term operatively associated" as used herein and in the claims in connection with the transmission of power from a centrifugal lever member to a coupling element, or vice versa as the case may be, for rotation of one by the other is intended to include within its scope all such possible devices which will readily occur to one skilled in the art.

It will be noted that in the modifications described above the centrifugal lever members are arranged transversely of the axis of rotation of the coupling elements. This is preferred in that compactness and simplicity of construction are assured by such arrangements. However, it will readily be understood that the invention may be practiced with a disposition of such elongated centrifugal lever members substantially parallel to the axis of rotation of the coupling members with one or more centrifugal lever members being floatingly associated with one of the coupling members at a plurality of places for rotary movement therewith, and the provision of suitable means for automatically causing the lever members to be fulcrumed selectively and alternately This clamping. may be obtained by a pair of half shoes 53, 53

at such places at different speeds, and operative driving association of the centrifugal lever members with the other coupling member for rotational driving of the latter by the former; wherebe attained in different speed ranges withrota tional driving of one of the coupling members from the other through the medium of such centrifugal lever members.

Such structure is shown by way of example in Figs. 15 to 18, inclusive. The coupling element or plate 2 i4 rotatably mounted on the portion ii of shaft i isprovided with a pair of spaced apart longitudinally extending plates ll, 1!! which may be made integral therewith or secured thereto in any suitable fashion, such as by screws or the like. The plates 10, 1!! are rigidly held in spaced apart position by fulcrum pins 222, 222 and 222, 222 anchored in position by screws 32-22. A pair of centrifugal lever members 22!, 22! are fioatingly disposed between the plates 10, ill with pins 222, 222 and 222, 222 respectively received in substantially radially outwardly extending arcuate slots 224, 224 and 225,

225 in the centrifugal lever members as shown.

any suitable means such as pins 12-12 anchored to or in recesses in the centrifugal lever members.

A sleeve 2I2 splined on to the portion I! of shaft II carries a cam plate 12 which may be made integral therewith as shown. The cam plate 12 is provided with an opposed pair of substantially radially extending arms. 14, 14 each of which has a cam surface 15 sloping away from the direction of rotation assuming a counterclockwise rotation of the structure when viewed from the driving side as shown in Fig. 16. Each centrifugal lever member 22! carries on the end thereof on the driving side a cam follower 12 such as a pin as shown which rides against the cam surface 15. In operation of the device shown in Figs. 15 to 18 incl., the centrifugal lever members 22!, 22! are biased inwardly at the fulcrum pins 222, 222 by reactive torque of the rotor of the apparatus being driven such as a magneto rotor through the sleeve 2!2, cam arms 14, 12 and pins 16, 18, which are pulled to radially. inward positions and held therein by virtue of the shape of the cam surfaces 15, 15 until such biasing force, is overcome by centrifugal force acting on the lever members.v

In such positions the pins 222, 222 are in fulcrum floating positions and the pins 222, 222 are in fulcruming positions. When the biasing force due to rotor torque is overbalanced by centrifugal force in a certain speed range the centrifugal lever members 22!, 22! are pivoted outwardly about fulcrumpins 222, 222 with the lever members biased to radially inward positions thereat by the springs 1!, 1!. This causes the pins 16,

inwardly a limited distance thereby permitting the angular advance of driven shaft ID to be retarded to a certain extent.

It will be noted that the ends of the plates 12, 1!) may overhang the cam plate 12 and its arms 14, 14 to limit rotary movement of the latterwith respectto the former.

In Figs. 19 and 20 is shown a coupling structure featured by centrifugal lever members adapted alternately to act as levers of the first and-second classes automatically to obtain advance and retard shifting of the angular relationship between driving and driven coupling members. By way of example the driving coupling element may comprise a spur gear 2 I4 suitably joumaled, such as by a sleeve I1, upon a portion of shaft In which has an intermediate splined portion I! interfitted with a sleeve 2I2. Opposed cam arms 2", 2! 2 are fixed to or carrled by the sleeve 2I2 comprising the driven coupling member. As in previous modifications the shaft II! is adapted to drive the rotor structure of the device, such as a magneto, to be driven through the coupling mechanism. An end plate 222 is suitably fixed to the gear 2 for rotation therewith by two pairs of pins 12, 222 and 12, 222 similarly if desired to the mounting of the end plate 22 by the pairs of fulcrumpins I22, I22 and I22, I22 in the modification shown in Figs. 8 to 12, incl. With the coupling mechanism viewed from the magneto side as in Fig. 20 and rotating in a clockwise direction as so viewed, it will be noted that each centrifugal lever member 22! is provided with a slot 222, a camming portion at 221 and an abutment nose 11, all to one side of the center of gravity (0. g.), which in the case of the uppermost centrifugal lever member are all to the right of the center of gravity and are located relative to each other in the order named. Initially the pin 222 is biased in the slot 222 to the outermost part thereof by a compression spring 19 and the camming por-- tion bears against a surface of the arm 2I2 at 221 with the abutment nose 11 spaced from'the pin 12; Accordingly the rotor torque biases the centrifugal lever member 22! through the camming structure to its initial position shown in full lines at A until a speed range is reached where the centrifugal force overbalances the biasing force due to the rotor torque. Thereafter the centrifugal lever member acts as a lever of the first class pivoting around the pin 222 as a fulcrum in a fulcruming position in the outermost part of the slot 225. This will causethe camming portion at 221 angularly to advance thecam arm 2I2 of the-driven coupling member until the abutment nose 11 engages the pin 18 as a stop with the centrifugal lever member 22! in the position shown in dotted lines at B. This angular advance then obtains until a speed range is attained where the centrifugal force further increases sufficiently to overbalance the biasing force due to the compression spring 12 and thereafter the centrifugal lever member 22! will be fulcrumed about the pin 12 with the abutment nose 11 in engagement therewith and with the portion of the centrifugal lever member adjacent pin 222 moving outwardly until the compression spring 12 and the innermost part of the slot 225 cooperate to provide a stop for pin 222.

This second action is accompanied by a retarding movement of the camming portion at 221 which permits an angular retarding of the cam arm 2!2 and the driven coupling member connected thereto, with the centrifugal lever member acting as a lever of the second class and moving to the position shown in dot-dash lines centrifugal lever member may be caused to operate first as a lever of the second class and then as a lever of the first class with the fulcrumlng at the abutment nose 'll being provided by the compression spring between abutment nose 1! and pin 13, which spring is indicated by the numeral 80 in the diagrammatic showing in Fig. .24. With such a structure rotating in the direction indicated in Fig. 20, that is clockwise when viewed from the rotor side of the coupling device, first a retard and then an advance action is obtained. Guidance for such a compression spring 30 may be provided by angularly widening the abutment nose I1 and providing it with an elongated slot receiving pin 18 in the far end thereof with the other parts disposed in the positions shown in full lines in Fig. 20. Such slot could extend toward and terminate in an abutment end in the neighborhood of the position shown for the abutment face of nose I1 and such spring 30 would be positioned in that slot between pin 13 and the abutment end of the slot to provide a resilient fulcruming abutment.

Obviously for the camming structure between the centrifugal leve'r member 32l and arm 3| 3 shown in Figs. 19 and 20, a linkage which may be similar to that shown in Figs. 2 and 12, or a rack and pinion structure similar to that proposed in Figs, 13 and 14 may be substituted at the work locale 321. Such linkage may be a pushing rather than a pulling linkage, or vice versa, depending upon the direction of rotation of the device and as to which of the two coupling elements serves as the driving element with the other serving as the driven element. For example, if the centrifugal lever member 32l be the curves between the horizontal portions can be made to assume substantially vertical positions or contrastingly can be flattened out considerably as desired. The general requirements regarding biasing of the centrifugal lever member at the fulcruming places as outlined above in connection with various modifications will be applicable and proper selection thereof for the attainment of particular operating characteristics will now be apparent to one skilled in the art.

In Figs. 21 to 24, incl., are diagrammatically indicated some of the various operative possibilities of the present invention and the structure of various modifications herein disclosed. InFig. 21 is diagrammed structure similar to that shown ,in Fig. 2 wherein each of the centrifugal lever members may operate first as a lever of the third 1 class and then as a lever of the first class in atlinked to arm 3i3' such as by a link similar to link 23 at the work locale 321 and the gear 3 serve as the driving coupling element'while rotating counterclockwise as viewed in Fig. 20, first advance and then retard may be had with a member first acting as a lever of the second class and then as a lever of the first class, as is diagrammed in Fig. 24. Proper biasing of the centrifugal lever member 32l to attain such operation may be provided at pins 323 and I8 by omitting spring 19 and utilizing a compression spring at 80 orprovlding a compression spring at 80 having a more effective biasing force than the spring utilized at I9, whereby floating action at pin 323 is obtained before such action is obtained at pin 18.

It will be noted from Fig. 7 that there isa definite slope to the curve between the substantially horizontal portions thereof. This represents the rate of change of angular-shifting due to the rate at which the biasing is overcome by the centrifugal force. Obviously this can be altered as desired by proper design of parts and biasing means of any of the indicated modifications, for example by selection of biasing springs or structure constituting the biasing means having certain characteristics. By way of example,the portions of taining an advance and retard of the angular relationship between driving and driven coupling members.- a I In Fig. 22 a similar structure is diagrammed wherein the centrifugal lever member 2! is more forcefully biased at fulcrum pin 23 than at fulcrum pin 22 so that it will act first as a lever of the first class and then as a lever of the third class. With a structure similar'to that shown in Fig. 2 first an advance and then a retard could be had with such a leverage and biasing, if the coupling device is reversely' rotated, that is in clockwise direction when viewed from the rotor side as there shown. In such case the linkage obviously would act as a pushing linkage.

In Fig. 23 is diagrammed the operation of the structure shown in Figs. 19 and 20, wherein the centrifugal weight member may act first as a lever of the first class and then as a, lever of the second class to obtain first an advance and then a retard. v

In Fig. 24 is diagrammed the operation of a structure proposed above in connectionwith Figs. 19 and 20, wherein it is suggested that a compression spring be interposed between the pin 13 at the abutment/nose I1 with the omissionof or use of a weaker compression spring Win the slot 325 so that the centrifugal lever member may act first as a lever of the second class and then asa lever of the first class.

The mechanism as shown may readily be en-' cased by separate casing members or can readily be housed in a cup-shaped or flanged socket suitably mounted upon the structure of the 'driven or driving device. Such encasement may be obtained in the case of a magneto driven from an engine by providing a cup-shaped member upon the side of a magneto casing into which projects the driven shaft of the magneto, such cupshaped member loosel receiving the mechanism of the present invention with provision for freedom of action of the coupling elements and centrifugal weight members. By way of example the mechanism depicted in Figs. 9 and 10 is shown suitably encased in a casing suitably secured by screws 6666 to a casing 61 of a magneto unit with the cup-shaped member 65, if desired, being provided with a bearing unit 88 supporting one end of the rotor shaft ID. A suitable thrust washer is shown at 69. I

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An angular phase shifting drive coupling mechanism comprising, in combination, a driving element, driven element, a centrifugal weight member operatively connected tov one of said coupling members at a particular work locale, a pair of fulcrum means floatingly connecting said weight member to the other of said coupling members at two different places, one of said places being in a zone between said work locale and the center of mass of said weight member and the other place being outside said zone, each of said fulcrum means permitting said weight member to move outwardly a limited distance when centrifugal force is applied thereto, means biasing said weight member to an innermost position at one of said fulcrum means, said weight member being adapted to be biased to an innermost position at the other of said fulcrum means by rotation resisting force of a driven device, and spring means connected between said elements reducing the effective biasing force of such driven device, said biasing means and the net biasing force being adapted to be overcome by different centrifugal force values to cause said fulcrum means alternately to act each as a pivot point for said weight member to eifect different phase shifts of said elements with respect to each other at different speeds.

2. An angular phase shifting .drlve coupling mechanism comprising, in combination, a driving element, a driven element, an elongated centrifugal weight lever, means floatingly connecting said lever member to said driving element to provide a pair of members rotatable together with said lever member alternately operable at different speeds as a lever of the first class and a lever of another class, a link connected to said lever member, a crank arm fixed to said other element and pivoted to said link for rotational driving of that element by said lever member, said means comprising a fulcrum pin fixed on one side of said members fioatingly received in an elongated outwardly extending way in the other member for limited outward movement of said lever member, another pin fixed on one of said members spaced from a fulcruming abutment on the other of said members to be brought into coop erating contact for action as a fulcrum when said lever member is pivoted about said first-mentioned pin in the way, means biasing said lever member to a fulcruming position at said firstmentioned pin with said lever member in a fulcrum floating position at said second-mentioned pin whereby said pins selectively and alternately act as fulcrums for said lever with the latter acting at different speeds as a lever of the first class and a lever of another class.

3. An angular phase shifting drive coupling mechanism comprising, in combination, a driving element, a driven element, an elongated centrifugal weight lever fioatingly positioned transversely of the axis of one of said elements to form therewith two floatingly associated members, a pair of fulcrum means fixed at two different places on one ofsaidtwo members with the other having arcuate ways floatingly receiving portions of said fulcrum means for limited outward movement of said lever member, a link pivoted at another place to said lever member to one side to said other element and pivoted to said link, and means biasing said lever member at said fulcrum means to initial innermost positions, the biasing force of said biasing means being adapted to be overcome by different centrifugal force values to cause said fulcrum means alternately to act each in its cooperating way as a pivot point for said lever member to effect different phase shifts of said elements with respect to each other at different speeds,

4. An angular phase shifting drive coupling mechanism comprising, in combination, a coupling member for transmitting rotation to a driven member, a second coupling member for transmitting rotation from a driving member to said first coupling member, one of said coupling members comprising a rotary plate, a secondplate fixed to said first-mentioned plate in spaced apart relation thereto by a pair of singularly spaced ful-v crum pins, a centrifugal elongated weighted lever member located transversely of the axis of rotation of said members and between said plates with arcuate ways therein fioatingly receiving said fulcrum pins for limited outward movement of said lever member, means operatively associating said lever member with the other of said coupling members at a particular work locale to to an innermost position including spring means between said lever member and the fulcrum pin farthest from said work locale restraining outward movement of said lever member at that fulcrum pin, the biasing of said lever member at the fulcrum pin nearest the work locale being of less efiective force value than that of said spring means whereby said lever member is adapted to operate at relatively lower speeds as a lever of the third class and at relatively higherspeeds as a lever of the first class angularly to advance one of said coupling members relative to the other through a certain speed range and to retard it through a higher speed pling member for transmitting rotation to a driven member, a second coupling member for transmitting rotation from a driving member to said first coupling member, one of said coupling members comprising a rotary plate, a second plate fixed to said first-mentioned plate in spaced apart relation thereto by two pairs of angularly spaced fulcrum pins, a pair of centrifugal elongated welghtedlever members diametrically opposed to each other to attain dynamic balance with each located transversely of the common axis of rotation of said members and between said plates with each centrifugal member having a pair of arcuate ways therein and with one way of a pair of the ways fioatingly receiving one of a pair of said fulcrum pins and the other way of that pair floatingly receiving the other fulcrum pin of that pair for limited outward movement of each of said lever members, a pair of opposed crank arms fixed to the other of said coupling members, a pair of links with each pivoted at one end to one of said 0! s i firstp a e a crank arm fixed l6 biasing device mounted on each lever member adjacent the fulcrum pin farthest from said work second connecting means is located lying outside point and bearing against that fulcrum pin to bias operatively angularly advance the driven cou.-'

pling member relative to the driving coupling member and drive the former from the latter at a certain predetermined angular advancement through andin certain speed ranges and then angularly retard the forme relative to the latter to a smaller angle of advancement through ahigher speed range.

6. An angular phase shifting drive coupling mechanism comprising a rotatable drive element,

of said angle.

9. An angular phase shifting drive couplin mechanism comprising a coupling member for transmitting rotation to a driven member, a second coupling, member for transmitting rotation from a driving member to said first coupling member, a centrifugal elongated weighted lever meniber located transversely of the axis ofrotation of said members and having a center of mass, means operatively connecting said lever member at a work point to one of said coupling members for rotational movement of the latter by the former, a pair of fulcrum means floatingly con-. necting said lever member to the other of said coupling members, said lever member being adapted to move outwardly a limited distance at each fulcrum means when centrifugal force is applied thereto, said center of mass, said work point and said fulcrum means being located on different 7 angularly related radii, said center of mass radius and said work point radius defining an angle a rotatable driven element, a centrifugal weight member having a center of mass, at driving connection including a link connecting one end of said weight member to one of said elements, a pair of shiftable fulcrum means supporting said weight member on said other element for relative inward and outward shifting and pivotal movement relative to the axis of rotation of said other element, one of said fulcrum means being positioned in a zone between said center of mass and said drive connection and the other outwardly of said zone, and means biasing said weight inwardly toward the axis of rotation of said other rotatable element.

7. An angular phase shifting drive coupling mechanism comprising a rotatable drive element, a rotatable drivenelement, a centrifugal weight member having a center of mass, a rack and pinion driving connection between said weight member and one of said elements, a pair of shiftable fulcrum means supporting said weight member on said other element for relative inward and outward shifting and pivotal movement relative to the axis of rotation of said othe element, one of said fulcrum means being positioned in a zone between said center of mass and said drive connection and the other outwardly of said zone, and

means biasing said weight inwardly toward the axis of rotation of said other rotatable element.

8. A drive coupling mechanism comprising a rotatable driving element, a rotatable driven element, a lever having a center of mass, a first means connecting said lever and one of said elements for inward and outward shifting and pivotal movement of said lever relatively to the axis of rotation of said one element, a driving connection between said lever and the other of said elements for rotating said elements relatively upon movement of said lever, a second means con necting said lever and said one element for relative inward and outward shifting and pivotal movement of said lever relatively to the axis of rotation of said one element, and means for biasing said lever inwardly,,said center of mass, said first and second connecting means and said driv ing connection being located on different angularly related radii extending from a common point on the axis of rotation of said one element, the radius on which said firstv connecting means is located lying within the angle between the radii on which said driving connection and the center of mass are located, and the radius on which said within which is one only of the said fulcrum means radii, and means biasing said lever member to an innermost position at said fulcrum means, said biasing means being adapted to be overcome by different centrifugal force values.

10. An angular phase shifting drive couplingmechanism comprising, a rotatable driving member, a rotatable driven member coaxial with said drive member, a lever having a center of mass, a. motion transmitting connection between said lever and one of said members, means supportin said lever on the other of said members for inward and outward sliding movement relative to the rotational axis of said members and pivoting movement about two spaced apart points, said spaced apart points, said center of mass and said connection being located on different angularly related radii extending from a point on the axis of rotation of said other member, one radius only on which one of said pivot points is located lying within the angle between the radii on which said center of mass and said connection are located, and biasing means for urging said lever inwardly, said biasing means acting to cause said lever to pivot about one of said points to impart up to a maximum relative rotation of said drive and driven members in response to the centrifugal force exerted on said lever within one speed range, and to pivot about the other point in response to the centrifugal force exerted on said lever within a higher speed range to decrease the relative rotation of said drive and driven members to less than said maximum.

11. An angular phase shifting drive coupling mechanism comprising a rotatable drive element, a rotatable driven element, a centrifugal weight member having. a center of mass, a pair of shift able fulcrum means supporting said weight member on said other element for relative inward and outward shifting and pivotal movement relative to the axis of rotation of said other element, a driving connectionbetween said weight member and one of said elements for rotating said elements relatively upon pivotal movement of said weight member, said fulcrum means, said center of mass and said rotary connecting means being located on difierentangularly related radii, one

of said fulcrum means radii being positioned with- 1y toward the axis of rotation of said other rotatable element.

12. An angular phase shifting drive coupling mechanism comprising a rotatable driving element, a rotatable driven element, a centrifugal weight member having a center of mass located on a radius extending from a point on the axis of rotation of said drive element, a pair of shiftable fulcrum means located on different radii extending from said point supporting said weight member on said other element for relative inward and outward shifting and pivotal movement relative to the axis of rotation of said other element, a driving connection between said weight member and one of said elements located on another radius, the radius on which one of said fulcrum means is located being positioned within an angle between the radii on which said center of mass and said drive connection are located and the radius on which the other fulcrum means is located being disposed outside of said angle, and spring means connecting said weight member and said other element at a point remote from said driving connection for biasing said weight inwardly toward the axis of rotation of said other element.

13. An angilar phase shifting drive coupling comprising a rotatable driving element, a coaxial driven element, a centrifugal weight member having a center of mass, 8. drive connection between said weight member and one of said elements, a first fulcrum pin and a cooperating aperture larger than said fulcrum pin connecting said weight member to the other of said elements, a second pin carried by said other element and engageable with one end of said weight member, said fulcrum pins, said center of mass and said one end of said weight member being located on different angularly related radii extending from a common point on the axis of rotation of said one element, said first pin radius lying in the angle between the center of mass radius and the driving connection radius and the second pin radius lying outside said angle, and spring means at said first pin biasing said weight member inwardly toward the axis of rotation of said other element.

14. An angular phase shifting drive coupling comprising a rotatable driving element, a rotat able driven element, a pluralityof centrifugal weights, each having a center of mass, a pair of shiftable fulcrum means supporting each weight member on one of said elements for relative inward and outward shifting and pivotal movement relative to the axis of rotation of said other ele ment, a driving connection between each of said weights and the other of said members for rotating said elements relatively upon pivotal movement of said weights, said fulcrum means, said center of mass and said driving connection of each lever being located on different angularly related radii extending from a common point on the axis of rotation of said one element, the

radius on which one of said fulcrum means is located lying within an angle between theradii on which said center of mass and said driving connection are located and the radius on which the other fulcrum means is located lying outside said angle, and means for biasing said weight members inwardly to cause them to pivot about one of their fulcrum means in one rotary speed .range and about the other of their fulcrum means in another speed range to shift the angular phase relationship of said elements up to a predetermined maximum angle in a lower speed range and then reduce the angular phase relationship in a higher speed range.

15. An angular phase shifting drive coupling device comprising a rotatable driving element, a rotatable driven element, a lever movable in response to centrifugal force and having a center of mass, an operating driving connection between said lever and one of said element for rotating said elements relatively upon movement of said lever, a pair of spaced apart shiftable fulcrum means connecting said lever to the other element, said fulcrum means, said center of mass and said driving connection being located on different angularly related radii extending from a common point on the axis of rotation of said one element, said fulcrum means radii being disposed on opposite sides of said center of mass radius and said driving connection being disposed on the opposite side of one of said'fulcrum means radii from said center of mass radius, and means biasing said lever inwardly in opposition to centrifugal force.

16. An angular phase shifting drive coupling device comprising a rotatable drive element, a rotatable driven element, a lever movable in response to centrifugal force and having a center of mass, an operative driving connection between said lever and one of said elements, a pair of spaced apart shiftable fulcrum means connecting said lever to the other element, said fulcrum means, said center of mass and said driving connection being located on dilferentangularly related radii from a common point on the axis of rotation of said one element, said fulcrum means radii both being disposed to one side of said center of mass radius, said driving connection radius being disposed between said fulcrum means radii, and means biasing said lever inwardly in opposition to centrifugal force.

LLOYD H. SCO'I'I'.

7 CERTIFICATE OF C ORREC TION- Patent No. 2,595,5L l1 January 22,- 19LL6.

LLOYD H. SCOTT;

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follons: Page 5, second coluxim, line 19, for "shorter" read -stronger--; page 8, first column, line 1+5 claim 2, for "pivoted" read -connected--; line 14.5, after the word "one" strike out "side; line 59, .after "lever" insert --member--; and that the said Letters Batent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signedand sealed this 16th day or April, A. 'D. 19LL6.

Leslie Frazer First Assistant Commissioner oi Patents. 

